My parents are immigrants from a country where Russian is widely spoken, and as a little kid I learned both Russian and the language of the country I was born in and live in. I've always spoken with my parents in Russian, and as a kid I could practice Russian because I consumed media (mainly cartoons) in Russian and interacted with Russian-speaking immigrant communities (as in real life communities).
Then as a teenager I stopped interacting with those communities and my Russian started stagnating, but at the same time I learned English (third language) by using the internet and consuming media in English instead. Later, I started learning Japanese (fourth language) because I have a strong interest in Japanese media, but my Russian started getting rusty.
I see my parents every day since I live with them, but I avoid having deep or serious conversations with them because I don't want to embarrass myself with poor Russian output, and I'm nervous whenever they invite me for a video call with their relatives who stayed in their country.
I've decided that I want to change this. I don't want to keep embarrassing myself in front of my parents and I want to be able to smoothly talk with them and my other relatives again. I want to restore my Russian skills, and preferably polish them to a decent adult level.
For reference, my pronunciation is native-like, and I have a general intuitive grasp of the grammar. In terms of output, my real problem is a lack of vocabulary. However, my comprehension is much, much better than my output skills, and a large part of that is probably because many words resemble words from English or my country's language (which is also Indo-European), so I can intuitively understand them even if they're not in my output vocabulary yet.
Something that makes this easier is that there's a lot to choose from to practice Russian - Russia is famous for having its own huge online bubble, and there's a lot of original Russian content including famous literature, and there are also lots of Russian translations of non-Russian content. In theory I could use their translations of Japanese content (which even includes anime fandubs), but since I started consuming Japanese media untranslated, it feels wrong to use any translations. (And by the way, for comparison, despite everything, my Russian is still better than my Japanese)
There are also many Russian visual novels, some of which have gained fame in the English sphere, but I have a deep-rooted aversion to non-Japanese VNs.
I think that I should start making some time for consuming content in Russian, and exploring Russian online spaces. Hopefully I don't have to sacrifice a lot of Japanese practice for that. And maybe I'll find out that Russian forums and imageboards are better than English ones, who knows.